This research is aimed at using genetic approaches to study development in the cellular slime mold Dictyostelium discoideum. The approaches will be divided into two types, those based on formal genetics and those based on selecting for mutations in specific functions. In the formal genetics section we will attempt to improve the para-sexual method by obtaining drug resistant mutants necessary to build a tester strain and by studying the mechanism of mitotic recombination in order to develop better mapping methods. In the second part of this proposal we attempt to develop selective methods to obtain mutations in specific cell functions. In particular we will attempt to get mutants which 1) affect the ability of the amebae to initiate the developmental program, 2) affect the normal cell recognition mechanisms and 3) affect cell movement and contractile mechanisms.